Rapid and Reproducible Characterization of the Wavelength Dependence of Aquatic Photochemical Reactions Using Light-Emitting Diodes,Environmental Science & Technology Letters

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Rapid and Reproducible Characterization of the Wavelength Dependence of Aquatic Photochemical Reactions Using Light-Emitting Diodes
Environmental Science & Technology Letters ( IF 8.9 ) Pub Date : 2021-03-18 , DOI: 10.1021/acs.estlett.1c00172
Collin P. Ward ₁ , Jennifer C. Bowen ₂ , Danielle H. Freeman _{1,

3} , Charles M. Sharpless ₄

Affiliation

Arguably, the largest knowledge gap in the aquatic photochemistry discipline is the wavelength dependence of sunlight-driven reaction rates in surface waters. Here, we introduce a new light-emitting diode (LED)-based approach to directly quantify the wavelength dependence of aquatic photochemical reaction rates. The LEDs generate narrow-banded, spatially uniform light at five wavelengths (275, 309, 348, 369, and 406 nm), with irradiances that are stable and easily adjusted to desired levels. Strong agreement was observed between irradiance measurements in each LED reactor using chemical actinometry and spectroradiometry. Apparent quantum yield (AQY) spectra of photochemical oxygen consumption by Suwannee River organic matter were determined four times across a six-month period. The shape and magnitude of the AQY spectra were highly reproducible, as indicated by strong exponential fits (R² ≥ 0.98) and low variability in oxidation rates across the four trials (coefficient of variation = ∼10%). This LED-based approach is cost effective, high throughput, and portable, allowing a broader community to study the wavelength dependence of aquatic photochemical processes in more detail than was previously possible. We anticipate that this approach will substantially advance our understanding of the wavelength dependence of photochemical reactions in surface waters and improve the accuracy of kinetic models.

中文翻译：

使用发光二极管对水生光化学反应的波长依赖性进行快速和可再现的表征

可以说，水生光化学学科中最大的知识鸿沟是地表水中阳光驱动的反应速率的波长依赖性。在这里，我们介绍了一种基于发光二极管（LED）的新方法，可以直接量化水生光化学反应速率的波长依赖性。LED会在五个波长（275、309、348、369和406 nm）处产生窄带，空间均匀的光，并具有稳定且易于调节至所需水平的辐照度。使用化学光化法和分光光度法在每个LED反应器中的辐照度测量之间观察到很强的一致性。在六个月的时间内，四次确定了Suwannee河有机质的光化学耗氧量的表观量子产率（AQY）光谱。AQY光谱的形状和大小可高度重现，[R ² ≥0.98），并在整个四个试验的氧化速率低变化（变化=〜10％系数）。这种基于LED的方法具有成本效益，高吞吐量和便携性，从而使更广泛的社区能够比以前更详细地研究水生光化学过程的波长依赖性。我们预计这种方法将大大提高我们对地表水中光化学反应的波长依赖性的理解，并提高动力学模型的准确性。

更新日期：2021-05-11

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